Elo Win Probability Calculator
See the expected score and an estimated win, draw and loss chance for any two chess ratings, with the Elo formula and the FIDE probability table.
The interactive elo win probability calculator loads here. It runs in your browser and is free to use.
What the Elo formula predicts
The Elo system predicts an expected score, not a single result. If your expected score is 0.64, you should average 64 points out of every 100 games against that opponent, counting a draw as half a point.
The formula depends only on the rating difference D (your rating minus your opponent's):
Expected score = 1 / (1 + 10^(−D/400))
Equal players expect 0.50. A 100-point edge gives about 0.64, 200 points about 0.76 and 400 points about 0.91. FIDE uses an official table built from a normal curve; it is shown next to the formula and differs by at most a couple of hundredths.
Wins, draws and losses
Elo itself does not say how often a game is drawn, so the win, draw and loss split is an estimate from a simple model. Draws are more common between strong players and in slow games, and less common when the rating gap is large. The model starts from a base draw rate that rises with the average rating, scales it down for rapid, blitz and bullet, and shrinks it as the gap grows. Wins and losses are then set so that wins plus half the draws equal the Elo expected score exactly. Treat these percentages as a rough guide, not data.
Worked example
A 1700 plays a 1500 in a classical game. D = 200, so the expected score is 1 / (1 + 10^(−0.5)) = 0.76. The average rating is 1600, which gives an estimated base draw rate of about 24%; with a 200-point gap that becomes about 17%. The 1700 is then estimated to win about 67%, draw 17% and lose 15% of the time.
Frequently asked questions
How many rating points is a 75% expected score?
About 191 points. Each extra 400 points multiplies the odds of scoring by 10, so 400 points gives roughly 91% and 600 points about 97%.
Can a lower-rated player be the favorite?
Not by rating alone. Ratings from different pools, time controls or rating systems can't be compared directly, though, so convert them first with the rating converter.
Why are the draw percentages labelled as estimates?
The Elo system only predicts the total score. The draw rate depends on time control, level, opening choice and the players' style, so we use a simple approximate model rather than a precise one.
Does the formula work for online ratings?
Yes, Glicko-2 ratings like Chessyo's use the same 400-point scale for the expected score, with an extra adjustment for how certain each rating is.
More rating calculators
- Performance Rating Calculator — Calculate your tournament performance rating (TPR) with the FIDE dp table, the linear rule of 400 and an exact Elo solution from your opponents and score.
- FIDE Rating Calculator — Free FIDE Elo calculator: enter your rating, K-factor and results to see your rating change, expected score and new rating under the 2024 FIDE rules.
- Chess Rating Converter — Roughly convert chess ratings between Chessyo (Glicko-2), FIDE and US Chess. A clearly labelled estimate to compare online and over-the-board ratings.